LOS ANGELES - Pop singer Mariah Carey and rapper Nicki Minaj will leave American Idol after just one season as judges on the singing contest show, following on the heels of long-time judge Randy Jackson who left amid a TV ratings slump.

"Thank you American Idol for a life changing experience! Wouldn't trade it for the world! It’s time to focus on the Music!" Minaj said on her Twitter page on Wednesday.

Carey's departure was also announced on Twitter by her public relations firm PMK BNC, which said the singer 'says goodbye 2 Idol' as she prepared to embark on a world tour.

Carey, 43, joined the judging panel with Minaj, country singer Keith Urban and Jackson, a music producer, for the show's 12th season.

Carey reportedly earned $18 million while Minaj's salary was reported to be $12 million and Urban was at $8 million for the season.

Carey and Minaj, 30, grabbed headlines throughout the season for their on-camera arguments and off-camera feuding, with Carey saying in January that she had hired extra security following threats reportedly made against her by Minaj.

Despite the added star power of Carey, Minaj and Urban, the show's ratings slumped to the lowest in 12 seasons, with the May 16 season finale of American Idol drawing 14.2 million to see vocal powerhouse Candice Glover win the competition.

Fox released statements following the announcements of both judges.

"Mariah Carey is a true global icon - one of the most accomplished artists on the planet - and we feel extremely fortunate that she was able to bring her wisdom and experience to the American Idol contestants this season," Fox said.

"Nicki Minaj is a superstar who brought a level of honesty and passion to American Idol and who had a tremendous positive impact on so many contestants this season. Given her extremely busy career, we understand and respect her decision and wish her the best," the network added after Minaj's announcement.

Jackson announced this month he would not return to the show next season. It was unclear whether Urban would.

Pop singer and actress Jennifer Lopez and Aerosmith frontman Steven Tyler left American Idol in 2012 after two seasons and used their increased visibility from the show to relaunch their music careers.

Fox, which is owned by News Corp, will also lose reality programming Chief Mike Darnell, who said last week he would leave at the end of June. Darnell shepherded American Idol into a ratings juggernaut since its debut in 2002.